1. Field of the Invention
The present invention relates generally to a key for use in an upright piano and so on, and more particularly, to a key which has a weight fixed therein to give a required touch load.
2. Description of the Prior Art
Generally, in a keyboard-based musical instrument, particularly, an acoustic piano such as an upright piano, a weight is fixed in a key to provide a desired touch load (static load) for the key. Conventionally, the weight is typically made of lead. As illustrated in FIG. 1, generally, in an upright piano, a weight 32 made of lead of a predetermined size molded into a cylindrical shape is embedded into a embedding hole 33 formed through a key body 52 made of wood of a key 30 at a predetermined position behind a balance pin (not shown), and caulked from both sides for fixation in the key body 31. The lead is employed as the weight in this manner because the lead has a high specific gravity (approximately 11.3) among other metals, is inexpensive, and exhibits high flexibility and ductility which facilitate molding and works as mentioned above.
In the conventional key 30 described above, lead is used as the material for the weight 32 for the reasons mentioned above. However, since lead is an injurious material, it is desirable that an alternative material is used for substitution for lead. Also, the weight 32 is fitted into the embedding hole 33 formed through each key body 31 and fixed by caulking on both sides, and the caulking is required for each key, the works involved in the fixation of the weight 32 are quite laborious. Also, since the weight 32 is fixed by caulking, the key body 31 is highly frequently susceptible to cracking and the like due to an impact applied to the embedding hole when the weight 32 is fixed in the key body 31 by caulking, resulting in an increase in the manufacturing cost.
The present invention has been made to solve the aforementioned problems, and it is an object of the invention to provide a key which is capable of effectively giving a touch load to the key, simplifying works involved in the fixation of a weight, and reducing the frequency of troubles such as cracking of a key body to reduce the manufacturing cost, while using an alternative material for substitution for lead as a material for the weight.
To achieve the above object, the present invention provides a key for a musical instrument characterized by comprising a swingable key body formed with an embedding hole; and a weight made of an alternative material having a specific gravity equal to or larger than a predetermined value, other than lead, and including a knurled portion on the outer peripheral surface thereof in the longitudinal direction, wherein the knurled portion is press-fitted into the embedding hole to fix the weight in the key body.
In this key, the weight is made of an alternative material having a specific gravity equal to or larger than a predetermined value, other than lead, and has the knurled portion on the outer peripheral surface thereof in the longitudinal direction. Then, the knurled portion is press fitted into the embedding hole formed through the key body to fix the weight in the key body, with the knurled portion applying a pressure to the embedding hole, thereby giving a touch load to the key. Also, since the weight can be fixed in the key body only through press-fitting into the embedding hole, the works involved in fixation is simplified, as compared with a conventional method which fixes a weight in a key body by caulking on both sides.
In addition, since the knurled portion of the weight is limitatively formed in part of the weight in the longitudinal direction, it is possible to limit a pressure to the embedding hole, while ensuring a required holding force of the weight, to reduce the frequency of troubles such as cracking of the key body.
Preferably, in the key set forth above, the key body comprises a front plate in a rear end portion on the top thereof, and a capstan wire implanted on the front plate, and the embedding hole extends through the front plate in the vertical direction to reach the key body.
In this preferred embodiment of the key, the embedding hole is formed through the front plate attached in a rear end portion on the top of the key body, i.e., at the position furthest away from a key fulcrum. It is therefore possible to highly effectively give a touch load to the key when a weight must be fixed in a portion of the key body behind the key fulcrum, as is the case with an upright piano. Generally, the front plate is made of a wood material harder than the key body, and the knurled portion has a large holding force, so that it is possible to reduce the frequency of troubles such as the weight coming off, by press fitting the knurled portion into the front plate, rather than press fitting it into the key body. Further, since the capstan wire is implanted on the front plate for attaching the capstan on the upper end thereof, the implantation of the capstan wire, the formation of the embedding hole, and the fixation of the weight can be efficiently carried out through simultaneous works by installing a machine for implanting the capstan wire and a machine for embedding the weight side by side in the longitudinal direction of the key body, thereby reducing the manufacturing cost.